A number of medically useful compositions comprise two or more ingredients that for optimal results should not be mixed together until shortly prior to use. In some instances, at least one of the ingredients is a solid, often a powder, while at least one of the other ingredients is a liquid in which the solid ingredient is to be dissolved. Therefore, it is desirable to have an applicator that can easily deliver multiple-component formulations for use in the body, which applicators are capable of keeping the individual components separated during storage and mixing them prior to application.
Use of a dual-ingredient composition can be accomplished with a conventional syringe by first loading one ingredient into the syringe, then adding the second ingredient, shaking the syringe or otherwise agitating the contents to achieve mixing, and subsequently dispensing the resulting mixture in the usual manner. This procedure, however, presents substantial shortcomings, including contamination and loss of sterility. For example, using a conventional syringe of the kind that is filled through a fill needle connected to the outlet orifice of the syringe, it is necessary to replace the needle after the first ingredient has been drawn into the syringe in order to avoid contamination of the supply of the second ingredient. Even then it may be difficult to complete the procedure without rendering the outlet portion of the syringe non-sterile, e.g., by extended contact with air. Another technique that may be employed utilizes a syringe of generally conventional construction in which one ingredient has initially been loaded into the syringe, usually followed by a sterilization procedure. Again, however, it is often rather difficult to load the syringe with the second ingredient without undermining the sterile characteristics of the syringe. Moreover, in both of these procedures the user's manipulative steps are complex enough that some difficulty may be experienced.
One approach to this problem is described in U.S. Pat. No. 5,080,649, incorporated by reference herein in its entirety. Therein is described a hypodermic syringe which has an elongated tubular body having a front end adapted to carry a needle, a rear end, and a bypass between the ends, wherein a front partition piston defines with the front end a front compartment adapted to hold a substance and a rear piston defines with the front piston a rear compartment adapted to hold a fluid miscible with the front-compartment substance; and the front piston is displaceable into a middle position in the bypass for fluid communication between the compartments.
Some medical sealants are examples of medically useful compositions which comprise two or more ingredients that are not mixed together until shortly prior to use. Medical sealants and adhesives play an important role in helping patients recover from surgery or trauma. In particular, sealants and adhesives are useful in treating patients suffering from a variety of internal or topical conditions, including lacerations, tears, wounds, ulcers, anastomoses, and surgical procedures. Sealants or adhesives can generally be used in any indication or application for which a suture or staple is presently used, and the sealant or adhesive often provides a better outcome than a suture or staple. Sealants or adhesives can also be applied more quickly to the injury site and often provide a better seal over the wound, and ultimately improved healing, in comparison to a conventional suture or staple.
There are at least two medical sealant/adhesive products, CoSeal and DuraSeal, currently on the market which are based on hydrogel formulations. Both products comprise multiple components housed in separate containers. CoSeal Surgical Sealant (CoSeal) is composed of two synthetic polyethylene glycols (PEGs), a dilute hydrogen chloride solution and a sodium phosphate/sodium carbonate solution. The DuraSeal Dural Sealant System consists of components for preparation of a synthetic, absorbable sealant and an applicator for delivery of the sealant to the target site the sealant is composed of two solutions, a polyethylene glycol (PEG) ester solution and a trilysine amine solution. However, the products have shortcomings because the devices need to be assembled at the time of use and they utilize static mixing systems that allow the hydrogel formulation to gel within the mixing nozzle, precluding a start-and-stop application technique.
Fibrin glues are also sold in packaging and applicator systems that are similar to those used for CoSeal and DuraSeal. One example is Baxter's Tisseel. Tisseel VH [Fibrin Sealant] consists of a two-component fibrin biomatrix that offers highly concentrated human fibrinogen to seal tissue and stop diffuse bleeding.
Baxter also offers different types of applicators, for example, Duploject; Easyspray; and DuploSpray MIS. Duploject is a reconstitution device that offers needle free easy preparation. Easyspray is a disposable set consisting of a dual-lumen connector hose, a sterile filter, two spray heads and a clip to be attached to the Duploject plunger for gas activation. DuploSpray MIS applicator is a disposable spray applicator consisting of a stainless steel shaft, dual lumen spray tubing, sterile filter and two replaceable spray tips.
Further, Micromedics, Inc., a medical device manufacturer in St. Paul, Minn., manufactures an endoscopic spray system for biomaterials called the FibriJet®. FibriJet® incorporates a gas-assisted spray system. Spraying of fibrin glues are also discussed in the patent literature; see: U.S. Pat. Nos. 5,474,540; 4,874,368; and 5,368,563; all of which are hereby incorporated by reference. See also U.S. Pat. No. 4,735,616, hereby incorporated by reference, which describes a twin bypass syringe for the delivery of fibrin glue products.